Reliable, consistent and predictable power is necessary in many commercial and non-commercial applications and as such, back-up power generation systems are gaining in popularity. In some situations, a main power source (such as public utility power) is connected to the electrical system of a building or facility via an electrical panel (or circuit box) that contains a plurality of switches or circuit breakers, where at least one of the plurality of switches is placed in-line with the main power source to allow for the main power to be connected to and disconnected from the building as desired. In some cases, it may be desirable to have a back-up generator (or other secondary power source) for back-up power. As such, a back-up generator may be connected to the electrical system of the building or facility via the same electrical panel (or circuit box), where another of the plurality of switches or circuit breakers is placed in-line with the back-up generator to allow for the generator to be connected to and disconnected from the building as desired. Thus, the main power source and the back-up generator source are connected to the building or facility in a parallel fashion.
This parallel connection allows for one of the parallel circuits to be disconnected while the other of the parallel circuits is connected. This parallel configuration is important because for safety and compliance reasons it is required by local building codes and national electric codes that only one source of power is connected at any one time. If both the main power source and the back-up generator power source are connected at the same time, then back feeding may occur resulting in damage to the components connected to the system, fire and/or electrocution of a worker working on the power line. As such, devices meant to prevent or limit the occurrence of multiple power sources being connected to one system at the same time have been developed and implemented in commercial and non-commercial applications.
One such device currently in use is an automatic transfer switch which is placed in-line with both the main power source and a back-up power source. The transfer switch is configured to sense when the active power source (either the main power source or back-up power source) loses power. After a predetermined amount of time following the loss of power, the transfer switch then disconnects the source that lost power and connects the source with power. For example, if a main power source loses power for a period of time, then the transfer switch will disconnect the main power source and connect the back-up power source.
Unfortunately however, some systems do not have an automatic transfer switch due to the cost of installing a permanent back-up generator and automatic transfer switch and thus, rely on portable back-up generators which typically require human intervention to switch between the public utility power source and the back-up power source. This introduction of human intervention introduces the possibility of one power source being inadvertently connected while the other power source is active and connected. This is undesirable and may result in back feeding, damage and/or death from electrocution.